Zipp 303S wheels 2020

Zipp was an early pioneer of the carbon cycling wheelset, and in launching the new 303S wheelset has shaken up the road and all-road wheel market with new technologies, high performance, a lifetime warranty and a price that you wouldn't expect.

It is quite refreshing to have a new wheelset released, and especially one from a major brand like Zipp, that doesn't just make claims about wind tunnel aerodynamic performance. The reality is that wind tunnel testing isn't the real world, and figures can be picked and chosen to suit the specific wheel. Instead, Zipp has tried a different approach – one that aims to replicate real riding, looking at all major areas that affect riding speed: wind resistance (aerodynamics), gravity, rolling resistance and vibrational losses. Zipp calls these four factors 'Total System Efficiency'.

> Buy now: Zipp 303S wheels 2020 from Sigma Sports for £839.00

The new 303S model wheelset uses some firsts for Zipp, including tubeless compatibility using straight-sided rim walls, also known as hookless. These might be a one-off, but are more likely a first step with more wheelsets within the Zipp range to follow with similar technology over the coming months.

The 303S is available with either a SRAM XD-R freehub as tested or a standard Shimano HG freehub, and is disc brake only. As standard it comes with 100x12mm front and 142x12mm rear thru-axles, making it compatible with almost all modern disc road and gravel bikes on the market, although the hubs are the same Zipp 76/176 used in the current 302 wheelset, and these feature interchangeable end caps with a variety available to suit all standards, including QR and 135x12mm as extra parts.

Our test wheelset came in almost exactly on the claimed weight of 1,540g.

Another big step for Zipp is the retail price of £985, making this the first carbon wheelset from Zipp to retail under the £1,000 point price. That makes it even more surprising to see a more affordable wheelset as a launch for newer technology – as it's more often the opposite.

Another change are the graphics: no longer will there be an option of black or white logo, at least in the case of these 303S model wheels. It looks clean and defined without being too in-your-face. Eagle-eyed fans may have seen team Movistar riders sporting the new graphics on other Zipp wheelsets, so this may be indicative of a change across the range.

As well as being the cheapest carbon wheelset that Zipp has produced, the 303S rim is also the first of its carbon rims to be manufactured outside of the US, being made in the SRAM Taiwan manufacturing site where they also manufacture many other carbon components.

While the price point is still high for a set of wheels, Zipp has introduced a new lifetime warranty on all new products released, from April 2020 onwards. This includes a lifetime warranty for defects for the original owner and also lifetime impact and damage replacement, although a cost may be applicable depending on the exact damage cause and the country you are in, as is often the case with other brands who offer a similar policy. Essentially, Zipp says that if you are using the wheels for their intended purpose, if anything were to happen to them then the damaged part will be repaired or replaced. So no Danny Mac style riding perhaps, but you can take these off-road onto gravel trails with confidence.

303S vs 302

Looking at the differences versus the outgoing 302 wheelset, there is a 155g drop in weight, which accounts for the gravity section within the Total System Efficiency and the one that is easiest to measure. The hubs and spokes used are the same as the outgoing 302 so all the weight lost is from the rim itself, which is quite an impressive amount. This weight loss is also at the outer edge of the rotational inertia and will feel far more significant than if it were at the centre of the wheel.

The new 303S rim shape is wider than the 302, both externally to 27mm but also internally, with a 23mm bead-to-bead measurement (up from 16.5mm on the 302), something that is possible as they are solely for disc brakes.

There is a maximum tyre pressure recommendation that is lower than I have seen before for a road wheelset – just 72psi – although Zipp is clear to state that this is mostly to promote the benefits of lower pressures, and assuming the correct tyres are used, tyres are not likely to blow off the rim as some people might fear.

The outer rim shape is also new: it's still 45mm deep but goes from a U-shaped rim to slightly more V-shaped. That might seem backwards given the trend in recent years, but perhaps shows that aerodynamics is not the sole goal for the 303S wheelset, as other factors, such as weight and strength, were considerations in designing the new rim.

Straight sides

Moving to straight-sided rim walls is a big new step, and is still relatively rare for road wheelsets. These are designed for tubeless-ready tyres only (both road and gravel), and originally came from mountain bike wheels – like the Zipp 3Zero Moto mountain bike rims – though we have seen some adoption within the road/gravel market, most prominently through ENVE with the AR and more recent Foundation series of wheels.

Unlike other road wheelsets that feature a straight-sided tubeless rim wall, Zipp doesn't put any restriction on the brand of tyre used, unless the tyre specifically states incompatibility on hookless rims.

If you want to run tubes it is still possible, so long as you use a tubeless-ready tyre, although this does defeat the purpose somewhat. Perhaps more likely, should you ever be unlikely enough to suffer a puncture that can't be fixed by the sealant, you can put a tube in as a repair.

Tyre sizing and compatibility

For the new 303S, Zipp's recommended tyre size for road use is 28mm, with a minimum recommendation of tyres with a stated width no narrower than 110% of the internal bead-to-bead measurement, so a 25mm would be OK if that was preferable. The recommendation comes from testing, and Zipp claims this will be the fastest size overall for road use. No size recommendations are made for off-road/gravel use, because of the widely different conditions that people tend to ride – UK gravel being very different to US gravel, for example – but a suggested maximum of 50-55mm covers almost all gravel tyres and bikes.

For the majority of my testing I used 28mm Schwalbe Pro One TL tyres. Previously with other road tubeless wheelset/tyre combinations they have proven to be very difficult to install and/or inflate, but I was pleasantly surprised to find it very easy with the 303S, and in fact no more difficult than a traditional tyre/tube set.

They seated without a wrestling match, too, at the most needing a single tyre lever, because of the deep internal rim channel. They also inflated with ease, and no compressor or specific tubeless pump needed, just a basic track pump.

The Zipp's wider internal rim might well have an impact on tyre width, and many will increase beyond their stated size. Once inflated, the 28mm Schwalbes measured 31mm, although it's worth pointing out that these were the 2019 version of the Pro Ones, not the newer 2020 "souplesse" versions, which are designed specifically for larger, more modern rims and likely to inflate closer to their stated size.

> Buyer’s Guide: 25 of the best tubeless wheelsets for under £1,000

I also tested the wheels with Continental's 25mm GP5000 TL, which inflated to measure 27.5mm, and various WTB gravel tyres, all 40mm, which inflated up to 42mm.

Currently there are no defined parameters for tubeless road tyres from ERTRO or ISO standards, so the wheelset has no standard to conform to, but Zipp is open in saying that it believes something will be forthcoming and it is working with tyre manufacturers with an ISO guideline being the main priority, and this could be where the 110 per cent tyre size to internal rim measurement will fall in the future.

Lower pressure

The use of a wider tyre has many benefits, as you can see in this video, and can in theory give reduced rolling resistance because of the shorter overall contact patch; rolling resistance is also reduced by decreasing the contact path deflection when used at the recommended tyre pressures from Zipp, which may be lower than many riders are used to.

> Why you need to switch to wider tyres

The lower pressure helps to reduce vibrational losses, as the tyre is in theory better able to conform to imperfections in the road, and being tubeless, lower pressures are possible with a far lower risk of punctures.

> How to choose your tyre pressure

For several years we have seen a tendency for riders to lower tyre pressures as tyre sizes have increased, and going under 100psi is now the norm. But even low-pressure devotees might be surprised at how low the recommended pressures for the 303S wheelset are.

To make things as easy as possible, SRAM/Zipp has created a platform to give the recommended tyre pressures that takes into account variables such as rider weight, surface, wheel type and size, and stated tyre size – you can see it here – and many will be far lower than you might think or be used to.

For me at around 64kg (143lb), the recommended pressures for road use with a tyre labelled 700x28 is just 53psi (3.65 bar) front, and 57psi (3.93 bar) rear. The online calculator takes account of all measurements and even road conditions.

Zipp likens the pressure recommendations to suspension within the mountain bike market, where there is often a pressure table on suspension forks and shocks as a guide, though it's seen as a starting point for riders – the exact pressure preference will depend on individual riding styles, road surfaces and preference to an extent. The same is true of the tyre recommendations: a useful starting point.

How do they ride?

Moving away from claims and calculators to how they are to ride, my first impressions are very positive. Under hard accelerations and sprints there is no noticeable flex laterally – something that's easy to verify, given that there is barely a millimetre of frame clearance on the test bike used. Under the hardest accelerations or out-of-the-saddle hill efforts there was occasionally a tiny noise from the brake rotor, but as parts other than just the wheels themselves come into play, it's not possible to isolate it to just the wheelset.

Overall, the feeling is of a very responsive wheelset.

Another noticeable feature is how stable they feel in real-world, changeable winds. Throughout testing and in a range of weather conditions, even with sudden gusts and those unexpected sidewinds from a gateway, the 303S remained easy to control with no sudden movements, even in stronger gusts. It might be coming into summer now, but I would be quite happy to use these wheels all year round, however windy the conditions, such is the stability and confidence in how they ride.

Although I was initially sceptical of running such low pressures, going from my usual 70-75psi (tubeless road) down to the recommended 51/57psi the feeling was positive. If you were to jump straight down from a 25mm tyre at 100psi it will no doubt feel quite different, but to me the tyres didn't feet soft or squirmy even under hard cornering.

Comfort and grip will depend on the exact tyre used, but any rubber at this pressure will feel comfortable compared to a tubed 25mm tyre. Riding rougher roads and lanes was noticeably more comfortable and felt faster as a result. The combination of lower recommended pressures and the straight-sided design might make some people worry that it isn't safe, but after more than 2,000km with the wheels, at no point during riding did I have any 'burp' or feeling that the tyre moved off the rim.

Are they fast? I made sure to test them on a wide variety of roads and in all conditions, and as a wheelset that can suit anything they certainly do feel fast. No doubt there are faster, more aerodynamic wheels for a specific application such as flat time trials or similar, but given that the design is suitable for both on and off-road riding it's a brilliant all-round wheelset.

> Buyer’s Guide: 21 of the best disc brake road wheelsets

The Zipps might not be designed as an out and out road race wheelset within the pro peloton, but it would seem ideal for events like the Classics and Paris-Roubaix, where low pressures are used, and it would have been interesting to see if the 303S would have made an appearance there, perhaps used by Movistar, one of the pro teams running SRAM groupsets and Zipp wheelsets.

If there is one criticism it is that the freehub pickup is slower than some wheelsets and freehub designs. Using a 3-pawl, 32-tooth ratchet setup is sufficient for most applications, and in normal road riding you are unlikely to notice a difference unless you have come from a hub design with many more engagement points. (The Shimano option is also a 3-pawl design with the ratchet in the hub.) It is most evident on bumpier roads and when climbing or at slower speeds.

Value

This is Zipp's most affordable carbon wheelset, but there are cheaper options out there. Hunt's 1,458g (claimed) 4050 Carbon Aero Disc wheelset is £819, and JRA's Mahi Mahi 40mm disc wheels are £850 (1,490g). Both of these have three-to-five-year warranty options, though, whereas Zipp now offers a lifetime warranty on 2020 wheelsets for the original buyer. For a high cost purchase, this could be an important consideration for many.

Conclusion

The 303S is an extremely impressive and versatile wheelset, offering reasonable weight with on and off-road capabilities. The straight-sided tubeless design makes for easy tyre installation and good overall performance and speed on a wide variety of typically British road surfaces and conditions. For riders who have already embraced the benefits of tubeless, or are ready to start, these wheels are impressive.

Verdict

Technology ahead of the curve but on point in terms of performance and price – the wheels of the future, now